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Abstract:

A method of fabricating a fluidic device comprises providing a fluidic
device including a body having a surface and one or more channels located
in the body. Recesses are defined on said surface. The one or more
channels can have respective boundaries. A layer of adhesive including
one or more panel-shaped pieces having a pattern based on the pattern of
boundaries of the channels can be formed and applied on the surface of
the body. It is further controlled that the layer of adhesive has
respective boundaries surrounding the boundaries of the one or more
channels.

Claims:

1. A method of fabricating a fluidic device, the method comprising:
providing a fluidic device including a body having a surface and one or
more channels located in the body and defining recesses on said surface,
the one or more channels having respective boundaries; forming a layer of
adhesive including one or more panel-shaped pieces having a pattern based
on the pattern of boundaries of the channels; and applying the layer of
adhesive on the surface and controlling the layer of adhesive has
respective boundaries surrounding the boundaries of the one or more
channels.

2. The method of claim 1, wherein the forming a layer of adhesive is
using a known amount of adhesive on the surface and then applying
pressure in a controlled manner to form a uniform layer.

3. The method of claim 1, wherein the controlling the layer of adhesive
has respective boundaries surrounding the boundaries of the one or more
channels is controlling an offset defined among boundaries of the layer
of adhesive and the boundaries of the one or more channels.

4. The method of claim 3, wherein the forming a layer of adhesive and
applying the layer of adhesive are performed by deposition of a
controlled amount of adhesive on the surface and by application of a
pressure on the adhesive.

5. The method of claim 1, wherein before applying the layer of adhesive,
the body is provided with protrusions which protrude from the surface and
surround the one or more channels, the protrusions separating the layer
of adhesive from the one or more channels.

6. The method of claim 5, wherein the surface comprises depressed regions
which accommodate the layer of adhesive and define said protrusions, said
protrusions being able to avoid contact between the layer of adhesive and
fluid passing through the one or more channels.

7. The method of claim 1, wherein the layer of adhesive is formed in such
a manner that a small offset is left between boundaries of channels and
boundaries of the layer of adhesive.

8. The method of claim 1, wherein pressure is applied on the layer of
adhesive to define a sharp boundary of the layer of adhesive mating with
the one or more channels.

9. The method of claim 1, wherein the layer of adhesive is applied only
on selective zones of the surface and defines thermal guards for a fluid
passing through the one or more channels.

10. The method of claim 1, wherein different layers of adhesive are
applied on the surface.

11. A fluidic device comprising: a body having a surface and one or more
channels located in the body and defining one or more recesses on said
surface, the one or more channels having respective boundaries; and a
layer of adhesive placed on the surface, wherein the layer of adhesive
includes one or more panel-shaped pieces having a pattern which is based
on the pattern of boundaries of the one or more recesses.

12. The fluidic device of claim 11, wherein the surface is an exposed
surface of the body.

13. The fluidic device of claim 11, further comprising a substrate and
wherein the surface is bonded to the substrate by means of the layer of
adhesive.

14. The fluidic device of claim 11, wherein the body includes protrusions
which protrude from the surface and surrounds the one or more channels,
such protrusions separating the layer of adhesive from the one or more
channels.

15. The fluidic device of claim 14, wherein the surface has depressed
regions which accommodate the layer of adhesive and define said
protrusions, said protrusions being able to avoid contact between the
layer of adhesive and fluid passing through the one or more channels.

16. The fluidic device of claim 11, wherein a small offset is interposed
between boundaries of the one or more channels and boundaries of the
layer of adhesive.

17. The fluidic device of claim 11, wherein a plurality of panel-shaped
pieces of the layer of adhesive are applied on respective selective zones
of the surfaces and define thermal guards for a fluid passing through the
one or more channels.

18. The fluidic device of claim 11, wherein the layer of adhesive of
different material are applied on the surface.

19. The fluidic device of claim 11, the fluidic device being a microchip.

20. A fluidic device comprising: a body having a surface and one or more
channels located in the body and defining recesses on said surface, the
one or more channels having respective boundaries; and a layer of
adhesive, structurally independent from the body and including one or
more panel-shaped pieces having a pattern which is based on a pattern of
boundaries of the channels such that a boundary of the layer of adhesive
surrounds the boundaries of the one or more channels.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Patent
Application 61/426,664 titled "Fabrication Method for Microfluidics with
Minimum Adhesive Exposure to Fluids" filed on Dec. 23, 2010, which is
herein incorporated by reference in its entirety.

FIELD

[0002] The present disclosure relates to fluidic or microfluidic devices
and to methods to fabricate microfluidic or fluidic devices.

BACKGROUND

[0003] Microfluidic devices and fluidic devices are often attached on
supporting substrates or apparatuses. Adhesive bonding has been used
extensively but it still remains cumbersome, expensive and time consuming
for microfluidic devices and fluidic devices having complex design of
channels and reservoirs. Especially when the structures are very small,
there is a significant problem of clogging the channels.

SUMMARY

[0004] According to a first aspect of the disclosure, a method of
fabricating a fluidic device is described, the method comprising:
providing a fluidic device including a body having a surface and one or
more channels located in the body and defining recesses on said surface,
the one or more channels having respective boundaries; forming a layer of
adhesive including one or more panel-shaped pieces having a pattern based
on the pattern of boundaries of the channels; and applying the layer of
adhesive on the surface and controlling the layer of adhesive has
respective boundaries surrounding the boundaries of the one or more
channels.

[0005] According to a second aspect of the present disclosure, a fluidic
device is described, the device comprising: a body having a surface and
one or more channels located in the body and defining one or more
recesses on said surface, the one or more channels having respective
boundaries; and a layer of adhesive placed on the surface, wherein the
layer of adhesive includes one or more panel-shaped pieces having a
pattern which is based on the pattern of boundaries of the one or more
recesses.

[0006] Further aspects of the disclosure are shown in the specification,
drawings, and claims of the present application.

[0008] FIG. 2 shows a layer of adhesive according to an aspect of the
present disclosure.

[0009]FIG. 3 shows a perspective view of a fluidic device according to an
embodiment of the present disclosure.

[0010] FIG. 4 shows a perspective view of a fluidic device according to an
embodiment of the present disclosure.

[0011] FIG. 5 shows a layer of adhesive according to an aspect of the
present disclosure.

[0012] FIG. 6 shows a perspective view of a fluidic device according to an
embodiment of the present disclosure.

DETAILED DESCRIPTION

[0013] With reference to the enclosed figures, a microfluidic device (10),
or microchip, for example a diagnostic cartridge, can include a main
solid body or block (12). The block (12) can include a flat surface (16)
and two fluid inlet or outlet ports (17), which can be located on a first
side (19) of the block (12). On the flat surface (16), e.g., on an
exposed surface of the block (12), the microfluidic device (10) can
include fluid channels (13), (14), (15), and more in particular, two end
channels (13), (15), which can be partially embedded in the flat surface
(16) and partially embedded in the ports (17), and a reservoir/cavity
(14), which can be located between and fluidly connected to the two end
channels (13) (15). The reservoir (14) can be defined with the two end
channels (13) (15), and more in particular with respective inlet mouths
of the channels (13) (15), open recesses or cavities on the external
surface (16), having respective boundaries.

[0014] According to an aspect of the present disclosure, the microfluidic
device (10) can include a layer of adhesive (30), which can be
structurally independent from the block (12) and can be applied on the
external surface (16). The layer of adhesive (30) can be designed a
priori based on the design of the channels of the body (12). In
particular, the layer of adhesive (30) can include one or more
panel-shaped pieces having a pattern (with respective boundaries) which
can match, correspond or be based on the pattern of boundaries of the
channels or cavities of the external surface (16). In other words, the
layer of adhesive (30) can include one or more thin structures matching
with the boundaries of the channels, without clogging the channels. The
adhesive can be applied in various ways known to those having ordinary
skill in the art. In the shown examples, the layer of adhesive includes
one or more substantially annular-shaped flat pieces.

[0015] In particular, a very thin layer of adhesive, previously designed,
can be deposited on the exposed surface (16). FIGS. 1-6 show possible
plate patterns for application of adhesive and respective layers of
adhesive. The adhesive can be applied on flat metal plate, separated from
the cartridge/block (12) or on a plastic part. Eventually different
surfaces of the fluidic device can be bonded to the substrates by the
same technique and by changing adhesives if needed. The adhesive
thickness can vary (e.g., few microns thick).

[0016] According to further aspects of the present disclosure, almost no
adhesive (30) comes in direct contact with fluid passing through the
channels (13), (14) and (15). In many cases, it can decouple adhesive
chemical compatibility from the fluids in the microfluidic devices. This
can be achieved from making very fine protrusions (24) (for example, few
microns in some cases or less) which can protrude from the surface (16).
Such structures can be readily made using various techniques including
injection molding. FIG. 4 shows a fluidic device including the
protrusions (24). Applying adhesive (using pad printing or otherwise like
from a dispensing robot) to outside of protrusion (24) allows bonding of
the cartridge while not allowing any/minimum interaction of fluid and the
adhesive. In other words, according to a further aspects of the present
disclosure, in order to delimit and confine the layer of adhesive (30),
the external surface (16) of the block (12) can have etched or depressed
regions (22) made around the end channels (13) (15) and/or the reservoir
(14). Such etched regions can define respective protruding walls or
protrusions (24) which protrude from the external surface (16) and can be
located along the end channels (13) (15) and/or the reservoir (14). The
etched or depressed regions (22) are able to receive or accommodate or
house a layer of adhesive (30) and have pattern corresponding to the
pattern of the layer of adhesive (30).

[0017] According to further embodiments of the present disclosure, the
layer of adhesive (30) can be cut or deposited in such a manner that a
small offset can be left between boundaries of channels (13) (14) and
(15) and the pattern of the layer of adhesive (30). In particular, after
deposition of the adhesive, a pressure can be applied on the adhesive to
obtain the layer. An amount of adhesive can be previously accurately
calculated to obtain said small offset and a defined thickness of the
adhesive. Application of pressure can allow small flow of adhesive but it
can stop due to fluidic effects and could form very sharp and well
defined boundary mating with channel and reservoir boundaries. In some
cases a very slight pressure might be needed due to the already thin
layer of adhesive. This process can be very fast, economical and
repeatable. While many other techniques to apply adhesive can fill the
whole space except for the areas where fluids are to be moved, this
methods of the present disclosure can allow controlled modifications of
the adhesive so that channels are sealed without clogging, while
minimizing use of adhesive supplies.

[0018] With reference to FIG. 6, a cartridge according to a further
embodiment of the present disclosure is shown. The cartridge of FIG. 6
includes a layer of adhesive (30) which can partially overlap the
external surface (16) and provide selective bonding regions. In
particular, such application can allow thermal guards to be automatically
built in microfluidic structures (e.g., PCR reactors). In fact, air can
be trapped in between adhesive layers and can then act as an insulator so
that heat transfer in lateral dimension along adhesive is reduced.

[0019] For example, one can use the same technique for application of
thermal or other epoxy on a large area with less thickness. Thus thermal
epoxy using this technique to bond metal plate bottom with polymer (for
example kapton) backed heater for qPCR can be applied. Also for two part
epoxies, one can have a two color pad printing style application in which
the areas of application overlap. Due to very small thickness, the mixing
should be sufficient for mixing and curing. UV adhesives can also be used
as well as many other kinds.

[0020] According to further aspects of the present disclosure, a method to
create adhesive layers is disclosed. In particular, adhesive of various
viscosities can be applied using dispensers, robots, pad printing, screen
printing and other techniques, to obtain an adhesive layer. The obtained
layer can be non-uniform due to surface tension and other effects. By
applying a known pressure, the adhesive (which can flow) can make a
uniform layer. The layers can automatically form a pattern due to fluidic
physics. The thin adhesive layer reaches the boundary. This makes
deposition of thin layers on large substrates extremely efficient, low
cost and quick. Therefore, according to an aspect of the present
disclosure, forming a layer of adhesive is applying known amount of
adhesive and then applying pressure in a controlled manner to form a
uniform layer.

[0021] According to further aspects of the present disclosure, the surface
of the chip can be flat but the protrusions can be made in the sealing
structure (e.g., flat metal of polymer surface). In that case the metal
surface can be milled, etched, stamped or modified to make the
protrusions or recesses.

[0022] The examples set forth above are provided to give those of ordinary
skill in the art a complete disclosure and description of how to make and
use the embodiments of the disclosure, and are not intended to limit the
scope of what the inventors regard as their disclosure. Modifications of
the above-described modes for carrying out the disclosure may be used by
persons of skill in the art, and are intended to be within the scope of
the following claims. All patents and publications mentioned in the
specification may be indicative of the levels of skill of those skilled
in the art to which the disclosure pertains. All references cited in this
disclosure are incorporated by reference to the same extent as if each
reference had been incorporated by reference in its entirety
individually.

[0023] It is to be understood that the disclosure is not limited to
particular methods or systems, which can, of course, vary. It is also to
be understood that the terminology used herein is for the purpose of
describing particular embodiments only, and is not intended to be
limiting. As used in this specification and the appended claims, the
singular forms "a," "an," and "the" include plural referents unless the
content clearly dictates otherwise. The term "plurality" includes two or
more referents unless the content clearly dictates otherwise. Unless
defined otherwise, all technical and scientific terms used herein have
the same meaning as commonly understood by one of ordinary skill in the
art to which the disclosure pertains.

[0024] A number of embodiments of the disclosure have been described.
Nevertheless, it will be understood that various modifications may be
made without departing from the spirit and scope of the present
disclosure. Accordingly, other embodiments are within the scope of the
following claims.